There has increasingly been a changeover to non-invasive forms of respiration (NW respiration) in the respiration or respiratory support of newborn and premature infants. The CPAP or NIV-CPAP respiration is one of these forms of respiration. Damage to the upper airways, which may develop due to intubation, shall be avoided by means of NIV respiration. Either nasal masks or prongs or nasal prongs are usually used in NIV respiration.
Nasal masks are usually masks manufactured from silicone rubber, which preferably enclose the patient's nose only and are provided with ports for the breathing tubes. Contrary to this, prongs usually have on their proximal side two small nasal tubes, which are inserted into the patient's two nostrils and have a port for an adapter for connection with the breathing tubes on their distal side. Intermediate tubes (hereinafter called “proximal” tubes), which are coupled at their distal ends with distal breathing tubes, which lead to the respirator or other respiration device, are frequently used in both nasal masks and prongs. The proximal intermediate tubes usually have a smaller cross section than the distal breathing tubes.
Prongs are predominantly used for NW-CPAP respiration. If, however, pressure sores develop on the nose and especially in the nostrils, the prongs may be temporarily replaced with nasal masks, which do not produce pressure sores because of their quality.
The prongs (and also the nasal masks) are attached by laterally arranged, stretchable bands (mostly by means of Velcro fasteners) to a headband or a cap, so that the prong can be held fittingly at the nose and it will not slip off if the patient is moving. The prongs are usually connected to a nasal adapter, which can be coupled at one of its ends to the distal prong port and at its other end to the proximal intermediate tubes. There are prongs of different sizes, depending on the size of the patient, the diameter of and the distance between the nostrils of the patient, into which the nasal tubes of the prong are inserted.
The respiration or respiratory support is usually performed by applying a continuous, positive airway pressure (CPAP). CPAP is a form of respiratory support that requires spontaneous breathing of the patient. Various methods are used to generate the CPAP. The pressure is generated by building up a high-velocity free jet (“jet”) in case of the so-called “jet method”. Besides, there are methods in which a ventilator feeds a more or less constant volume flow via the inspiratory tube into the breathing system, while an adjustable flow resistance is arranged at the end of the expiratory tube. The pressure develops as a consequence of this flow resistance and the friction in the expiratory tract of the breathing system. The adjustable flow resistance may be generated by a so-called water lock (known as “bubble CPAP”) or a regulated expiratory valve.
In all methods mentioned, the inhaled gas must be fed to the patient via tubes. The expired gas must be sent, at least in the method mentioned last, to the ventilator or to the water lock with tubes from the patient. However, the expired gas is usually sent away from the patient in the jet method as well to prevent CO2 from accumulating in the vicinity of the patient.
To keep the volumes and the compliance values of the gas columns as low as possible in the breathing tubes, the tubes of newborn and premature infants, but also of toddlers, are generally smaller than those of adults. For examples, tubes with internal diameters of 11 mm or 15 mm are used in pediatrics and neonatology, whereas tubes for adults practically have an internal diameter of 22 mm without exception.
The connection between the distal tubes (i.e., breathing tubes) and the prong or the nasal mask is usually brought about by so-called CPAP adapter systems (or nasal adapter systems or simply nasal adapters) especially in newborn and premature infants. It shall be mentioned only in passing that such nasal adapter systems may also be used in toddlers or adult patients. However, toddlers and adults frequently breathe through the mouth instead of through the nose, so that face masks are preferably used for respiration for adult patients.
Prior-art nasal adapter systems usually have two proximal tubes with a reduced internal diameter compared to that of the distal breathing tubes and a, for example, Y-shaped adapter headpiece. Various nasal adapter systems are known from the state of the art.
Thus, for example, WO 03/022341 A1 discloses a respiratory support device with a nasal adapter, which is provided with a removable prong, two ports for the breathing tubes and a sensor port. The prong in this nasal adapter has two nasal tubes, which can be inserted into the patient's nostrils. One drawback of the nasal adapter according to WO 03/022341 A1 is that the prong or the nasal tube of the prong can be adapted to different nose sizes (distance and diameter of the nostrils) of different patients only insufficiently at best. Even though the prong and the nasal tubes may be manufactured from a rubber or silicone material, this makes possible only a limited adaptation to different nose shapes (distance and diameter of the nostrils as well as angle of the nostrils relative to the head), so that a large number of different prongs must be kept ready. Great difficulties are caused, in particular, by the adaptation to the angle of the nostrils, because the correct angle of the prong being used can usually be determined only when the complete nasal adapter is placed on the patient's head. It may now happen that the nasal adapter is placed several times on the patient with different prongs until the optimally fitting prong with an optimal angle of the nasal tubes is found. Another drawback of the nasal adapter according to WO 03/022341 A1 is that the air flow is deflected by 180° at the junction between the proximal end of the adapter and the distal end of the prong. The removal of a desired quantity of air from the prong is adversely affected hereby, because the inspired air is pressed with a high impulse into the nasal tubes, as a result of which the patient's expiration is made difficult, which is a drawback especially in newborn and premature infants. Further, the prong has a relatively large dead space due to its design, as a result of which the newborn or premature infant will breathe in again a large portion of the previously expired air during a subsequent breathing cycle. Finally, the breathing tubes of the prior-art nasal adapter are relatively rigid and can be adapted to different head sizes and head shapes of patients with difficulty only.
DE 10 2009 016 150 A1 discloses a nasal adapter or a non-traumatic nasal tube for non-invasive respiratory support, in which the angular position of the entire nasal tube can be changed relative to the forehead support by means of a tilting holder. However, the angle of the nasal adapter or nasal tube relative to the nasal cannula cannot be adjusted. Even though the central tube of the nasal cannula is elastic and is provided with a flexible metal strip to make it possible to adapt the nasal cannula to the shape of the patient's head as best as possible, the degree of freedom obtained hereby is not sufficient for achieving an optimal angular adaptation of the nasal adapter or of the nasal tubes to the patient's nostrils. A further drawback is that corrugated pleated tubes are used in DE 10 2009 016 150 A1, which cannot be adapted continuously, on the one hand, and generate an increased flow resistance compared to a smooth tube due to the pleats present in the interior of the tubes, on the other hand Finally, the pleating of the tubes leads to the possibility of very great variations in the length and hence in the inner volume as well as the compliance of the tube between the original state and the adapted state, on the other hand. This usually has a highly disadvantageous effect on the control characteristics of the ventilator when generating the constant CPAP pressure. Since the nasal adapter has no partition between the inhalation gas and the exhalation gas, the functional dead space is very large.
A bar-shaped, plastically deformable element is arranged between the proximal breathing tubes of a nasal mask device in the solution proposed in DE 103 29 818 A1, and the curvature of these proximal tubes can be permanently changed with this element in order to make it possible to adapt the curvature of the tubes to the size of the head and the shape of the head as a result. The mask device shown in DE 103 29 818 A1 has a nasal mask, whose position relative to the proximal tubes cannot, however, be adjusted, so that the nasal mask can be adapted to the patient's nose only insufficiently. In addition, the breathing tubes must be deformed for reasons of handling (just as in the case of DE 10 2009 016 150 A1) before they are attached to the patient's head. Fine adaptation to the patient's head is difficult because of the forces to be applied for bending the proximal breathing tubes and therefore not practicable. However, precisely this fine adaptation is necessary to prevent the torques applied by the tubes on the nasal mask from leading to one-sided pressure loads in the face or on the nose and hence to possibly irreversible damage to the anatomy of the face.
US 2010/0147302 A1 pertains to a respiration system with a mask system, which has a nozzle assembly unit with two nozzles for connection with the nostrils of a patient. This nozzle assembly unit has a tubular structure and is provided at its opposite ends with two end areas, which can be rotated independently from one another relative to the nozzle assembly unit and are connected to the breathing tubes. The breathing tubes thus extend separately from one another on both sides of the patient's head. It may happen when the patient's head is moving that the nozzle assembly unit becomes detached from the patient's nose.
Finally, DE 202 06 692 U1 discloses, in general, a device for generating a continuous positive airway pressure with an adapter, to which a prong provided with nasal tubes can be attached. However, these nasal tubes are not adjustable, so that no angular adaptation of the nasal tubes to the patient's nostrils can be carried out in this device, either.
The connection between the distal tubes, which are connected with the respirator or other respiration device, and the proximal tubes of the nasal adapter system is usually brought about via conical plug-type connections. However, due to the frictional engagement, such plug-type connections also transmit torques, besides tensile forces and bending torques. This may lead to twisting and, in the worst case, even to occlusion of the proximal tubes of the nasal adapter system when the patient is turning.
As it becomes clear from the above explanations on the state of the art, the drawback of all prior-art nasal adapter systems is that they do not make optimal adaptation of the adapter system to the size and shape of the patient's head possible. In particular, no optimal adaptation of the coupled prongs or of the adapter itself to the nostrils of the patient being respirated can be achieved with the adapter systems according to the state of the art. The nasal adapter may become detached from the patient's nose in the worst case when the patient's head is moved. In addition, the coupling between the adapter and the prong is designed in all prior-art nasal adapters such that the airway resistance is not optimal and a relatively large, so-called dead space becomes established. The latter may lead to the patient rebreathing part of the exhaled air during a subsequent breathing cycle. The CO2 content in the breathing air will increase in this manner continuously during each breathing cycle especially in newborn and premature infants because of the small breathing air volume, because at least part of the air volume enriched with CO2, which remains in the dead space, is inhaled again during each breathing cycle. Finally, the nasal adapter systems according to the state of the art have a complex design, which makes the manufacture of the adapters complicated and expensive.